Both the Red Cross and Federal Emergency Management Agency (FEMA) rely on the system to decide where to direct people in disasters and how to get them there.

Schulsinger volunteers for an hour or more on most days updating the system’s map of more than 56,000 available shelters.

A check on Jan. 3 told him there were nearly 59,000 available that day, 60 of which were open. Three in Chico, Calif., were housing 700 people displaced by wildfires. Schulsinger suspected a shelter in Evansville, Ind., he is familiar with was serving flood victims, but a quick check showed it, too, was providing shelter in the aftermath of a fire.

A shelter’s location provides “a pretty good idea” of what kind of disaster is involved, he said. “If you see one in Ohio, 99 percent of the time it’s a fire or something along those lines.”

Consistent with the notion that “they do things differently there,” however, shelters in California open their doors in the aftermath of fires, mudslides, earthquakes “and the occasional tsunami,” Schulsinger said. They get “everything but the Zombie apocalypse,” he added, “and I wouldn’t rule that out.”

A 26-year volunteer for the Red Cross, Schulsinger’s stint on the map project began six years back when, while mapping shelters in the northern Miami, he discovered some of the “peculiarities” of the shelter system’s GPS-based system.

Among them:

“If somebody forgets to put a minus sign in front of a longitude (reading), your map comes out in Russia or China.”

If the latitude and longitude are reversed, “the map attempts to develop north of the north pole somewhere.” And because there is no such place on earth, it tries to map the shelter in space, “somewhere near Polaris” – in this instance, the North Star, not the shopping complex.

Schulsinger is glib about how he came to be the person primarily responsible for updating the system: Those he called about making fixes to the system “got fed up with me,” and fixed him by giving him the job.

A fairer take is that he brought to the work a willingness to explore problems in the kind of detail learned during a career at Huntington Instruments and YSI in Yellow Springs. “I was mostly in scientific instruments … in electrochemistry.”

What he learned gave him an appreciation not only for how complex systems work but those “peculiarities” that come with the territory.

If a shelter identified by a post office box number is entered the system, which requires a street address, “it maps to the nearest post office,” not the shelter.

If a shelter is described as being at the intersection of two streets, “the lookup button basically throws up,” and maps a random spot somewhere in the Zip Code.

If a school has changed its address to something like “1 Wildcat Way” and the county engineer has not made the change to the official county map, “again, it barfs,” Schulsinger said.

At other times, he finds himself bedeviled by searching for a shelter at a college or university. “There may be 75 buildings on the campus, and the address (usually an administration building) is never the shelter.” To solve this problem, he may consult a college map and find the right building.

In his problem-solving, Schulsinger often consults Google maps and satellite imagery to identify buildings.

On Jan. 3, he was tracking down a shelter at First United Methodist Church in Fort Dodge, Iowa. “That’s hill country there. I know that.”

Using his Google helpers, he found the street, tracked down the church by its shape, double-checked with a satellite photo and pushed a button.

“That’s the first one I’ve had to map this year.”

More often than churches, he searches out the silhouettes of schools, which “are usually good (shelters) because they have showers, kitchens and places to put down lots of cots.”

Typical users of the shelter system and its map are police and firefighters and staffs of the Red Cross and FEMA staff. But the system also has a digital app that has been downloaded by “a few million people” who live along Gulf Coast and in disaster-prone areas like the Gulf Coast and California.

At 66, Schulsinger, who for many years logged more than 1,000 volunteer hours, considers the 500 hours he logged on the shelter map in 2018 a down year. Then again, his Red Cross volunteer resume includes on-site work responding to floods in North Dakota, Minnesota and Southern Ohio; helping with 1998 effort to clean up Puerto Rico after Hurricane George; and carrying out communications and damage assessment in New York after the attacks of 9/11.

Although the opportunity to be a remote volunteer has extended his volunteering life, he’s found it brings a sense of remoteness as well.

“There are people who know that I’m working behind the scenes,” he said, though “some just know me by my initials,” MAS, which appear in the places he’s tweaked the map.

These days, Schulsinger does keep the company of a couple of worries. One is over who might take over his map work when he retires. A deeper worry involves the reliability of the GPS system itself, not just because it’s vital to the workings of the shelter mapping system but because it’s a vital part of our technological infrastructure.

“A solar flare could knock out GPS, enemy activity could knock out GPS,” he said.

If that were to happen, power grids, cellphone communications and a host of other systems could go haywire.

Should that happen, this man who knows complex systems, how they work, and what can happen when they don’t, says we’ll be dealing with more than peculiarities.